Update Python version requirements and fix compatibility issues

- Bump minimum Python version from 3.11 to 3.13 across all apps
- Add Python 3.11-3.13 test matrix to CLI workflow
- Document Python 3.11+ requirement in .env.example
- Fix Starlette Broadcast removal with in-process fallback implementation
- Add _InProcessBroadcast class for tests when Starlette Broadcast is unavailable
- Refactor API key validators to read live settings instead of cached values
- Update database models with explicit

apps/blockchain-node/requirements.txt

@@ -0,0 +1,27 @@
+# AITBC Blockchain Node Requirements
+# Generated from pyproject.toml dependencies
+
+# Core Framework
+fastapi>=0.111.0
+uvicorn[standard]>=0.30.0
+
+# Data & Database
+sqlmodel>=0.0.16
+sqlalchemy>=2.0.30
+alembic>=1.13.1
+aiosqlite>=0.20.0
+
+# WebSocket Support
+websockets>=12.0
+
+# Validation & Configuration
+pydantic>=2.7.0
+pydantic-settings>=2.2.1
+
+# Performance
+orjson>=3.10.0
+
+# Local Dependencies
+# Note: These should be installed in development mode with:
+# pip install -e ../../packages/py/aitbc-crypto
+# pip install -e ../../packages/py/aitbc-sdk